"I could not have done this without Daniela, I hear her face is everywhere!" he said through his family spokesman, after landing at Heathrow airport on Tuesday morning. "She is so brave and strong, seeing her and my family after this ordeal is the best thing that could have happened. I thank you all once again, this is very surreal.”

He also thanked the British embassy and the Foreign Office for their help in securing his release.

The Durham University PhD student, originally from Exeter, was sentenced on Wednesday after being arrested at Dubai Airport as he tried to leave on May 5.

The second, and more intriguing, reason for a raised eyebrow from the intelligence community, is the use of the term ‘Captain’. No such rank or appointment exists among Britain’s spies; they are simply known as ‘Officers’.

An official told reporters in Abu Dhabi that Mr Hedges was "100% a full-time secret service operative" who was in the country "to steal the UAE's sensitive security national secrets for his paymasters".

He said the Briton's pardon came in response to a letter from his family appealing for clemency and due to the historical close ties between the UK and UAE.

"His highness has decided to include Mr Matthew Hedges among the 785 prisoners released," he said.

"Mr Hedges will be permitted to leave the country once all the formalities are complete."

The UK takes a "neither confirm nor deny" approach to allegations of intelligence service membership, but Mr Hunt has previously said he has seen "absolutely no evidence" to suggest Mr Hedges is a spy.

Following the pardon, Ms Tejada, from Bogota in Colombia, said: "The presidential pardon for Matt is the best news we could have received.

"Our six-plus months of nightmare are finally over and to say we are elated is an understatement.

"That he is returning home to me and the rest of his family is much more than I was ever expecting to happen this week. I thank you all for your support."

Ms Tejada credited media coverage, support from British diplomats, Mr Hunt, academics and members of the public across the world for helping her husband's cause.

She continued to reject the accusation that he was a spy, telling BBC Radio 4's Today programme: "In my heart I know that he isn't."

Mr Hedges' release was confirmed after a family representative initially contradicted UAE officials who said he had been freed.

Mr Hunt said the UAE had made a "very important gesture" in pardoning Mr Hedges but described it as a "bittersweet moment" given that Briton Nazanin Zaghari-Ratcliffe remains detained in Iran, also accused of spying.

He told Today: "In a way it's a bittersweet moment as in Iran, another country in the region, we have Nazanin Zaghari-Ratcliffe, an innocent woman who is still in prison for nearly three years now.

"Indeed, there are other British citizens and other citizens from other countries also wrongly imprisoned in Iran also.

"So, you know the wonderful news about Matthew is also making us remember there are other people who are in a terrible state right now and we must never forget them either."

UAE minister of state for foreign affairs Anwar Gargash said the pardon would allow the two countries to "return our focus to the underlying fundamental strength of the UAE-UK bilateral relationship", the WAM Emirates news agency reported.

Dr Gargash said: "It was always a UAE hope that this matter would be resolved through the common channels of our longstanding partnership.

"This was a straightforward matter that became unnecessarily complex despite the UAE's best efforts."

Professor Stuart Corbridge, vice-chancellor of Durham University, said staff were "absolutely delighted" to learn of the news.

"It is paramount that he is now allowed to return home to Daniela and his family as quickly and safely as possible," he said.

Ms Tejada told Sky News she wanted to arrange a "winter barbecue" for her husband, which had been postponed from Spring due to his detention.